Dresden 2017 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 50: Poster: Organic Electronics and Photovoltaics, Molecular Excitations

CPP 50.16: Poster

Wednesday, March 22, 2017, 18:30–21:00, P3

Thermally Activated Delayed Fluorescence studied by Electroluminescence Detected Magnetic Resonance — •Sebastian Weissenseel¹, Nikolai Bunzmann¹, Benjamin Krugmann¹, Jeannine Grüne¹, Stefan Väth¹, Andreas Sperlich¹, and Vladimir Dyakonov^1,2 — ¹Experimental Physics VI, Julius Maximilian University of Würzburg, 97074 Würzburg — ²Bayerisches Zentrum für Angewandte Energieforschung (ZAE Bayern), 97074 Würzburg

The mechanism of thermally activated delayed fluorescence (TADF) in organic light emitting diodes (OLEDs) raised many questions with respect to the spins of the emitting exciplex states. In particular, whether the TADF mechanism is a spin-dependent process and, if yes, what is the mechanism of the triplet-singlet Up to now spin-sensitive measurements for OLED devices are scarcely presented in literature. Here, we investigate TADF OLEDs by electroluminescence detected magnetic resonance (ELDMR) in devices based on 4,4’,4”-Tris(N-3-methylphenyl-N-phenyl-amino)triphenylamine (m-MTDATA): Tris(2,4,6-trimethyl-3-(pyridin-3-yl)phenyl)borane (3TPYMB) exciplexes. The triplet states of this system energetically split in an external magnetic field. Microwave radiation, applied by a stripline, is absorbed at a resonant magnetic field and enhances the intensity of electroluminescence. Modifying experimental conditions, e.g. resonance frequency, temperature or microwave power, leads to detailed knowledge of the spin system and the underlying mechanism of the reverse intersystem crossing. This information will assist designing new cost-effective OLED materials.